Cold-pressed flaxseed oils: Characterization of cold-pressed flaxseed oils and products from their enzymatic transesterification with cinnamic and ferulic acids

The physicochemical and stability characteristics of seven cold-pressed flaxseed oils sold in New Zealand were investigated. The oils exhibited significant variations in their physicochemical characteristics. Four oils were found to be within the limit of good stability oil indices. The role of minor constituents in the oxidative stability of two selected flaxseed oils with different fatty acid composition and minor constituents was also investigated. It was found that phenolic acids present free in the oils played a dominant role in the oxidative stability of the oils. Enzymatic transesterification of triolein with the phenolic acids, cinnamic and ferulic, was conducted. The characterization of the resulting products where the phenolic acids were bound to the fat structure was carried out. This study using triolein as a model system was extended to flaxseed oil. A mechanism for the opposing protective effects of esterification of cinnamic and ferulic acids compared with the unbound acids was presented and the role of solvent in determination of free radical scavenging activity was investigated.